Methods: This was a retrospective review of multi-year quality assurance logs on cardiacarrest patients evaluated with point-of-care Echo during CPR, over a seven year period.All patients in cardiopulmonary arrest that presented when physicians trained in Echowere availabile and had quality assurance documentation completed, were eligible forenrollment. Patients for whom incomplete data was present in the logs were excludedfrom the study. This study took place at a busy emergency medicine department with alarge cardiac population and an approximate annual census of 80,000 visits per year.Emergency physicians (EPs), with hospital credentialing in point-of-care Echo, routinelyused ultrasound as part of their standard management of CPR patients. During all pulsechecks, nurses and physicians attempted to locate pulses while one EP performed a briefEcho of the heart with a compact ultrasound machine. Echo checks were limited to thetime available during pulse checks and ended when the treating EP ordered resumption ofchest compressions. Myocardial function was graded into normal ejection fraction (EF),mildly, moderately, severely depressed, negligible function and asystole as previouslydefined in the literature. If Echo suggested sufficient EF to generate blood flow but pulsecheck was negative, the carotid arteries were evaluated with Doppler when interferencewith resuscitative efforts could be avoided. Statistical analysis included descriptivestatistics and Cohen Kappa coefficient for agreement analysis.

​Results: A total of 693 pulse checks occurred concomitantly with Echo checks in 226patients. Of the 226 patients, 59 (26.1%) had resumption of spontaneous circulation at some point in their resuscitation based on pulse palpation and electrocardiographicmonitor tracing. A total of 178 (25.7%) Echo checks revealed an EF felt to likelygenerate a detectable blood pressure. In 47% (84) of those Echo checks, no pulses werepalpable. Conversely, in 31 (6%) pulse checks (when electrical cardiac activity was notedon the monitor) and a healthcare provider felt palpable pulses, the echo showed eithermyocardial standstill or negligible EF. Echo results and pulse palpation during pulsechecks showed poor correlation with a Kappa of 0.52.

Conclusions: In this study, Echo findings and pulse palpation results periodicallydisagreed when myocardial activity was present. When Doppler analysis of carotid flowwas possible in patients with adequate EF but no pulses, flow was always noted. Veryconcerning, in 6% of patients apparent palpable pulses occurred when Echo showed nomyocardial contraction or negligible EF

INTRODUCTION

Evaluation and treatment of patients in cardiopulmonary arrest has progressedsignificantly in the last four decades with the advent of cardiac resuscitation protocols,endotracheal intubation, central line placement and electric cardioversion. 1-4 However,clinicians managing cardiopulmonary resuscitations are typically doing so blindly. Whileelectrocardiographic monitoring provides a glimpse of the electrical activity of the heart,it tells the clinician little about actual myocardial function. 5 Thus, pulse checks are criticaland help determine if spontaneous circulation has resumed. In addition pulse checks willtypically decide whether chest compressions continue or not and if resuscitation isterminated.Typically, invasive arterial blood pressure monitoring is not available in patientsarriving to an emergency department or resuscitation area. Similarly, hospitalizedpatients that are not in an intensive care unit are unlikely to have any invasive monitoringin place. Since pneumatic blood measuring devices are inaccurate, slow to result andhave difficulty picking up low blood pressures, physicians typically have to rely onmanual pulse palpation during resuscitation. 6 However, there is growing evidence that ourability of accurately palpate a pulse is quite poor in these critically ill patients. 7,8 Somestudies indicate that physicians may accurately palpate a pulse in as low as 50% ofpatients. 9 This likely results from the innate inaccuracy of pulse palpation, the tenseenvironment of a cardiac arrest and also the trend toward obesity and morbid obesity inwesternized countries. In addition, low blood pressure and low flow states which requirevasopressor support, but not continued chest compressions, may be too difficult to detectby human hands in many cases.

Many intensivists, emergency physicians, surgeons and other clinicians havefound great utility in utilizing bedside echocardiography during cardiopulmonary arrestmanagement. 10-12 This reflects the ability of ultrasound to identify treatable causes ofarrest as well as aid in managing patient resuscitation. 13 Anecdotal experience, as well asprevious published studies suggest that there may be a discordance betweenechocardiographic findings and electrocardiographic findings as well as detection ofpulses. 14 This study sought to evaluate the frequency of apparent discordance betweenpulse detection by manual palpation and finding on echocardiography.

METHODS

Study DesignThis was a retrospective quality assurance log review using de-identified patientdata of ultrasound findings during cardiac arrest pulse palpation breaks. The study wasconducted at busy emergency department with a large high acuity cardiac population andannual census of approximately 80,000 patients. This study was IRB exempted due to itsretrospective quality assurance nature and use of de-identified data.All patients arriving in, or experiencing cardiopulmonary arrest while in theemergency department, without an indwelling arterial pressure monitor, were eligible forenrollment if they had complete data in the quality assurance logs. As part of standardpractice all cardiopulmonary resuscitations were managed with bedside emergencyechocardiography, when hospital credentialed physicians were available. Patients withincomplete quality assurance log data were excluded from the study. Quality assurancelogs were reviewed for cardiac arrest entries with completed EF estimate andcorresponding pulse check results by an experienced point of care ultrasound programdirector.

Arrest Echo ProtocolEach patient in cardiopulmonary arrest was scanned by a study physician duringpulse breaks. The treating physician was advised of echo finding as part of standardpractice, but the study physician did not make treatment recommendations. Bedsideultrasound examinations were performed only during pulse checks, which wereconducted by a nurse and treating physician or second nurse. In all cases, at least two

healthcare providers assessed for pulses at the same time. All pulse checks were madeeither at carotid artery or femoral artery locations. All efforts at performing an echo wereceased when the pulse check was stopped by the treating physician. Echo checkscontinued during pulse checks for the duration of the resuscitation as long as they did notinterfere with resuscitation efforts.Left ventricular function on echocardiography was graded into distinct categories:normal ejection fraction (EF), mildly (approximately 40 to 50%), moderately(approximately 20 to 40%), severely depressed (approximately 10 to 20%) and negligiblefunction (EF below 10%) as previously defined in the literature. 15 If Echo suggestedsufficient EF to generate blood flow but pulse check revealed no palpable pulses, thecarotid arteries were evaluated with Doppler, color and pulse wave, when interferencewith resuscitative efforts could be avoided.All ultrasound examinations of the heart during pulse checks were videotapedusing either SVHS video tape or DVD and stored for quality assurance review. Inaddition, ultrasound quality assurance logs were filled out with ultrasound findings andclinical outcome as part of standard practice. Emergency sonologists utilized phasedarray transducers with a range of 2.5 to 4 MHz using either as SonoSite 180 Plus, Titan,Micromaxx or M-Turbo compact ultrasound machines. Standard echocardiographywindows were utilized to image the heart. The subxiphoid window was utilizedpreferentially in order to avoid interference with resuscitation, the parasternal long andapical four chamber views were used if no useful subxiphoid image was obtainable.Transesophageal echocardiography was used when available, either on a SonositeMicromaxx or M-Turbo.

Main Outcome MeasuresPhysicians filled out standardized quality assurance logs. They recorded theresults of the pulse checks by team members and the corresponding emergency echofindings. For secondary measures, if left ventricular ejection fraction was felt to be above10% in the setting of absent pulses on palpation and the study physician was able toDoppler a carotid artery, presence of absence of flow was recorded. In addition, whenpulse wave Doppler was used the peak systolic velocity was recorded. Sonologists alsorecorded when manual pulse palpation revealed a palpable pulse, but emergency echoshowed either negligible that could not generate flow or complete absence of myocardialcontraction.

Statistical MethodsData were kept in an Access database (Microsoft Corporation, SeattleWashington). Prior to analysis, data were exported to an Excel spreadsheet andcommercially available statistical software was used to perform analyses. Statisticalanalysis included descriptive statistics and agreement analysis using Cohen Kappacoefficient.

RESULTS

A total of 693 pulse checks occurred concomitantly with Echo checks in 226 patients. Ofthe 226 patients, 59 (26.1%) had resumption of spontaneous circulation at some point intheir resuscitation based on pulse check and electrocardiographic monitor tracing. A totalof 178 (25.7%) Echo checks revealed EF of severely depressed or better and were felt tolikely generate a detectable blood pressure. In 47% (83.66) of these Echo checks, nopulses were palpable. Conversely, in 31 (6%) pulse checks on when electrical cardiacactivity was noted on the monitor and a healthcare provider felt palpable pulses, the echoshowed either myocardial standstill or negligible EF.

Carotid Doppler was obtained in 37% of cases when Echo showed severely depressed orbetter EF but no pulses were palpable. In these cases, all patients showed flow in thecarotid on both color and pulse wave Doppler. Echo results and pulse palpation duringpulse checks showed poor correlation. Echo results and pulse checks showed pooragreement with a correlation coefficient of 0.52. Comparing only the 178 patients notedto have echo based findings of adequate cardiac output the Cohen Kappa decreased to0.47.

DISCUSSION

Cardiopulmonary arrest has many etiologies, some of which are correctablethrough interventions such as pericardiocentesis and many that are not. However,identification of these correctable processes may be difficult simply based on physicalexamination and electrocardiographic evidence. The focus of many resuscitation effortsare patients with apparent electrical activity on a monitor, as they may hold out thehighest hope for successful resuscitation. 16 Over the past two decades, the use of Point ofCare Ultrasound to manage resuscitation has greatly improved the ability of clinicians toaccurately identify correctable causes of cardiac arrest in a variety of settings. 17 Recentstudies suggesting that focused ultrasound checks of the heart during CPR interfere withquality chest compression are likely to push more providers to relying on pulse palpationonly. 18,19 However, prior data has repeatedly suggested pulse checks are unreliable forresuscitation management, leaving providers who chose not to use ultrasound blinded tocardiac function in many cases.Pulseless electrical activity (PEA) occurs when a patient appears to have electricalactivity on a monitor, but no pulse can be palpated. Once thought to strictly indicatemechanical asystole in the presence of electrical activity, it is now clear that a portion ofthese patients have mechanical cardiac activity with blood pressures too low to result in apalpable pulse, in that specific individual. One study demonstrated that up to 41% ofpatients presenting with electrical activity but no pulse actually had mechanicalcontractions of the heart. 20 While survival rates for patients in PEA are poor, with onelarge study reporting 11% survival rate with only 62% of survivors having a good

neurological outcome, this group of patients are typically thought to have a higherlikelihood of survival than asystolic patients. 21 As the team managing the patient incardiopulmonary arrest strives to resuscitate the patient they are also seeking reversiblecauses of cardiac arrest. In PEA patients these include tension pneumothorax,hypovolemia, toxins, hypoglycemia, hypoxemia, acidosis, hypokalemia, hyperkalemia,hypothermia, cardiac tamponade, cardiac ischemia, pulmonary embolism, and trauma. 22Ultrasound can aid the resuscitation team by allowing visual assessment ofcardiac function as well are a more accurate evaluation for some the treatable causes ofPEA that are listed by both the AHA and European Council on Resuscitation. 23 Cardiactamponade from pericardial effusion can be readily identified by focused emergencyecho. 24 At the same time the provider can image the inferior vena cava to estimateintravascular fluid volume and even monitor change in volume during ongoingresuscitation. Cardiac contractility can be evaluated by emergency echo and may greatlyaid in goal directed resuscitation. Pneumothorax has been proven to be very accuratelyruled out and identified in multiple studies by point of care ultrasound. In cases of largepulmonary emboli, point of care ultrasound may detect intra-cardiac thrombosis, venousthrombosis or particular echo findings such as right heart strain on TAPSE and McConellsign, which may strongly point toward presence of PE. 25 In such cases, the resuscitationdirector may be more included to thrombolyse the patient given the evidence provided byultrasound. When complete mechanical cardiac stand still is noted on echo despiteseveral rounds of chest compressions and medications there is strong support thatsuccessful resuscitation is extremely unlikely. Terminating the resuscitative efforts earlierin such patients may save resources without compromising care.

In most situations of cardiopulmonary resuscitation, the code is continued untilfurther efforts are deemed futile and the resuscitation stopped or, in the minority, whenresumption of spontaneous circulation is noted. Unless the patient has already been inthe hospital or emergency department for some time and received an indwelling arterialblood pressure monitor, the only commonly accepted method of determining resumptionof spontaneous circulation is palpating a pulse.While patients with no cardiac output receive chest compressions and epinephrinea hypotensive patient may be taken along a different pathway of resuscitation. Not only isthe treatment of a hypotensive patient different from that of a patient in PEA, but CPRitself is not a benign intervention and may cause injury to the patient. Unnecessarytrauma to a critically ill patient could further complicate recovery if the patient survivesthe resuscitation. Frequent findings in patients having undergone CPR include lesions oftracheal structures and bony chest fractures. Less frequently encountered are lesions ofthe pleura, pericardium, myocardium and other internal organs and vessels. 26As this data indicates, disagreements between the ultrasound machine monitorscreen and manual pulse palpation are surprisingly common. The concept of actuallychecking the carotid artery for blood flow on color and pulse wave Doppler came out ofmultiple situations when disagreement occurred between staff that insisted on resumingchest compressions and physicians who ordered them stopped because of adequateestimated ejection fraction on focused echo. Such patients are most likely to be treatedwith vasopressors and fluids in order to elevate their blood pressure, but may be difficultto manage if providers are blind to their cardiac function. Our data further supports thatpulse palpation is inaccurate, in arrest situations, suggesting that providers may want to

add focused echo for additional information. In 37% of patients physicians were able toaccess the carotid artery after the echo, which reflected an ejection fraction felt to beconsistent with perfusion of the brain. In each case color Doppler confirmed the presenceof spontaneous blood flow with measurement on pulse wave Doppler ranging from 60 to105 cm/sec.Vascular ultrasound and neurology literature indicates that normal commoncarotid artery peak systolic flow velocities vary considerably, but tend to range from 55to 100 cm/sec. 27 Mean values in normal patients from the internal carotid are typically 54to 88 cm/sec, but some normal individuals can have peak systolic velocities up to 120cm/sec. 28 Values increase considerably for carotid stenosis. Regardless, the typical flowvelocity recorded in this study was quite near normal as previously defined. Multipleother factors affect carotid peak systolic velocities, such as potential stenosis in thevertebral arteries or the contralateral carotid. However, such fine details probably havelittle bearing in gauging if adequate circulation is produced by a beating heart, while nopulses are palpable. It is at this point that chest compressions may be terminated andpressors instituted or adjusted as in any critically ill, hypotensive patient.Exceedingly shocking was the fact that in 6% of cases a team member called out“I have a pulse” leading to cessation of chest compressions, when the heart was inmechanical standstill or had no viable contractile activity. We have noted anecdotally andrepeatedly that such confusion causes delays measured in minutes that may even last untila pneumatic blood pressure cuff finally fails to obtain a blood pressure and anotherprovider realizes no pulses are palpable. While additional evidence will need to beproduced, it is more and more compelling that ultrasound should be present at the bedside

of every patient undergoing cardiopulmonary resuscitation whenever possible. This canbe achieved in the most unlikely settings. The introduction of highly compact devices hasenabled clinicians outside of the intensive care units and emergency departments to useultrasound for evaluation of cardiopulmonary arrest patients. Focused ultrasoundutilization has been documented in the settings of pre-hospital ground and air ambulancesas well as disaster scenes and even sporting events.Limitations of the study include no invasive monitoring to compare pulsepalpation to actual arterial blood pressure. The study population was typical of diversewestern body habitus distributions and may not reflect findings in other populationsaround the world where pulse palpation may be more or less accurate. The retrospectivenature of the study is also an inherent limitation, although data was collectedprospectively for quality assurance tracking.In summary, data from this study suggests that disagreement between focusedecho and pulse palpation is a common occurrence. As suggested by previous studies andresuscitation algorithms hypotension and asystole have different treatment pathways andthere may even be potential harm from unnecessary chest compressions. While morestudies are needed, the inclusion of focused echocardiography into cardiopulmonaryresuscitation may provide valuable additional information not accurately obtained frompalpation of pulses.

CONCLUSION

In this study, Echo findings and pulse palpation results frequently disagreed when myocardial activity was present. When Doppler analysis of carotid flow was possible in

patients with a gradable EF but no pulses, flow was always noted. In a small percentage of patients apparent palpable pulses occurred when Echo showed no myocardial contraction or negligible EF.